drivers/md/dm-bio-prison-v1.c

   1 /*
   2  * Copyright (C) 2012 Red Hat, Inc.
   3  *
   4  * This file is released under the GPL.
   5  */
   6
   7 #include "dm.h"
   8 #include "dm-bio-prison-v1.h"
   9 #include "dm-bio-prison-v2.h"
  10
  11 #include <linux/spinlock.h>
  12 #include <linux/mempool.h>
  13 #include <linux/module.h>
  14 #include <linux/slab.h>
  15
  16 /*----------------------------------------------------------------*/
  17
  18 #define MIN_CELLS 1024
  19
  20 struct dm_bio_prison {
  21         spinlock_t lock;
  22         struct rb_root cells;
  23         mempool_t cell_pool;
  24 };
  25
  26 static struct kmem_cache *_cell_cache;
  27
  28 /*----------------------------------------------------------------*/
  29
  30 /*
  31  * @nr_cells should be the number of cells you want in use _concurrently_.
  32  * Don't confuse it with the number of distinct keys.
  33  */
  34 struct dm_bio_prison *dm_bio_prison_create(void)
  35 {
  36         struct dm_bio_prison *prison = kzalloc(sizeof(*prison), GFP_KERNEL);
  37         int ret;
  38
  39         if (!prison)
  40                 return NULL;
  41
  42         spin_lock_init(&prison->lock);
  43
  44         ret = mempool_init_slab_pool(&prison->cell_pool, MIN_CELLS, _cell_cache);
  45         if (ret) {
  46                 kfree(prison);
  47                 return NULL;
  48         }
  49
  50         prison->cells = RB_ROOT;
  51
  52         return prison;
  53 }
  54 EXPORT_SYMBOL_GPL(dm_bio_prison_create);
  55
  56 void dm_bio_prison_destroy(struct dm_bio_prison *prison)
  57 {
  58         mempool_exit(&prison->cell_pool);
  59         kfree(prison);
  60 }
  61 EXPORT_SYMBOL_GPL(dm_bio_prison_destroy);
  62
  63 struct dm_bio_prison_cell *dm_bio_prison_alloc_cell(struct dm_bio_prison *prison, gfp_t gfp)
  64 {
  65         return mempool_alloc(&prison->cell_pool, gfp);
  66 }
  67 EXPORT_SYMBOL_GPL(dm_bio_prison_alloc_cell);
  68
  69 void dm_bio_prison_free_cell(struct dm_bio_prison *prison,
  70                              struct dm_bio_prison_cell *cell)
  71 {
  72         mempool_free(cell, &prison->cell_pool);
  73 }
  74 EXPORT_SYMBOL_GPL(dm_bio_prison_free_cell);
  75
  76 static void __setup_new_cell(struct dm_cell_key *key,
  77                              struct bio *holder,
  78                              struct dm_bio_prison_cell *cell)
  79 {
  80        memcpy(&cell->key, key, sizeof(cell->key));
  81        cell->holder = holder;
  82        bio_list_init(&cell->bios);
  83 }
  84
  85 static int cmp_keys(struct dm_cell_key *lhs,
  86                     struct dm_cell_key *rhs)
  87 {
  88         if (lhs->virtual < rhs->virtual)
  89                 return -1;
  90
  91         if (lhs->virtual > rhs->virtual)
  92                 return 1;
  93
  94         if (lhs->dev < rhs->dev)
  95                 return -1;
  96
  97         if (lhs->dev > rhs->dev)
  98                 return 1;
  99
 100         if (lhs->block_end <= rhs->block_begin)
 101                 return -1;
 102
 103         if (lhs->block_begin >= rhs->block_end)
 104                 return 1;
 105
 106         return 0;
 107 }
 108
 109 static int __bio_detain(struct dm_bio_prison *prison,
 110                         struct dm_cell_key *key,
 111                         struct bio *inmate,
 112                         struct dm_bio_prison_cell *cell_prealloc,
 113                         struct dm_bio_prison_cell **cell_result)
 114 {
 115         int r;
 116         struct rb_node **new = &prison->cells.rb_node, *parent = NULL;
 117
 118         while (*new) {
 119                 struct dm_bio_prison_cell *cell =
 120                         rb_entry(*new, struct dm_bio_prison_cell, node);
 121
 122                 r = cmp_keys(key, &cell->key);
 123
 124                 parent = *new;
 125                 if (r < 0)
 126                         new = &((*new)->rb_left);
 127                 else if (r > 0)
 128                         new = &((*new)->rb_right);
 129                 else {
 130                         if (inmate)
 131                                 bio_list_add(&cell->bios, inmate);
 132                         *cell_result = cell;
 133                         return 1;
 134                 }
 135         }
 136
 137         __setup_new_cell(key, inmate, cell_prealloc);
 138         *cell_result = cell_prealloc;
 139
 140         rb_link_node(&cell_prealloc->node, parent, new);
 141         rb_insert_color(&cell_prealloc->node, &prison->cells);
 142
 143         return 0;
 144 }
 145
 146 static int bio_detain(struct dm_bio_prison *prison,
 147                       struct dm_cell_key *key,
 148                       struct bio *inmate,
 149                       struct dm_bio_prison_cell *cell_prealloc,
 150                       struct dm_bio_prison_cell **cell_result)
 151 {
 152         int r;
 153         unsigned long flags;
 154
 155         spin_lock_irqsave(&prison->lock, flags);
 156         r = __bio_detain(prison, key, inmate, cell_prealloc, cell_result);
 157         spin_unlock_irqrestore(&prison->lock, flags);
 158
 159         return r;
 160 }
 161
 162 int dm_bio_detain(struct dm_bio_prison *prison,
 163                   struct dm_cell_key *key,
 164                   struct bio *inmate,
 165                   struct dm_bio_prison_cell *cell_prealloc,
 166                   struct dm_bio_prison_cell **cell_result)
 167 {
 168         return bio_detain(prison, key, inmate, cell_prealloc, cell_result);
 169 }
 170 EXPORT_SYMBOL_GPL(dm_bio_detain);
 171
 172 int dm_get_cell(struct dm_bio_prison *prison,
 173                 struct dm_cell_key *key,
 174                 struct dm_bio_prison_cell *cell_prealloc,
 175                 struct dm_bio_prison_cell **cell_result)
 176 {
 177         return bio_detain(prison, key, NULL, cell_prealloc, cell_result);
 178 }
 179 EXPORT_SYMBOL_GPL(dm_get_cell);
 180
 181 /*
 182  * @inmates must have been initialised prior to this call
 183  */
 184 static void __cell_release(struct dm_bio_prison *prison,
 185                            struct dm_bio_prison_cell *cell,
 186                            struct bio_list *inmates)
 187 {
 188         rb_erase(&cell->node, &prison->cells);
 189
 190         if (inmates) {
 191                 if (cell->holder)
 192                         bio_list_add(inmates, cell->holder);
 193                 bio_list_merge(inmates, &cell->bios);
 194         }
 195 }
 196
 197 void dm_cell_release(struct dm_bio_prison *prison,
 198                      struct dm_bio_prison_cell *cell,
 199                      struct bio_list *bios)
 200 {
 201         unsigned long flags;
 202
 203         spin_lock_irqsave(&prison->lock, flags);
 204         __cell_release(prison, cell, bios);
 205         spin_unlock_irqrestore(&prison->lock, flags);
 206 }
 207 EXPORT_SYMBOL_GPL(dm_cell_release);
 208
 209 /*
 210  * Sometimes we don't want the holder, just the additional bios.
 211  */
 212 static void __cell_release_no_holder(struct dm_bio_prison *prison,
 213                                      struct dm_bio_prison_cell *cell,
 214                                      struct bio_list *inmates)
 215 {
 216         rb_erase(&cell->node, &prison->cells);
 217         bio_list_merge(inmates, &cell->bios);
 218 }
 219
 220 void dm_cell_release_no_holder(struct dm_bio_prison *prison,
 221                                struct dm_bio_prison_cell *cell,
 222                                struct bio_list *inmates)
 223 {
 224         unsigned long flags;
 225
 226         spin_lock_irqsave(&prison->lock, flags);
 227         __cell_release_no_holder(prison, cell, inmates);
 228         spin_unlock_irqrestore(&prison->lock, flags);
 229 }
 230 EXPORT_SYMBOL_GPL(dm_cell_release_no_holder);
 231
 232 void dm_cell_error(struct dm_bio_prison *prison,
 233                    struct dm_bio_prison_cell *cell, blk_status_t error)
 234 {
 235         struct bio_list bios;
 236         struct bio *bio;
 237
 238         bio_list_init(&bios);
 239         dm_cell_release(prison, cell, &bios);
 240
 241         while ((bio = bio_list_pop(&bios))) {
 242                 bio->bi_status = error;
 243                 bio_endio(bio);
 244         }
 245 }
 246 EXPORT_SYMBOL_GPL(dm_cell_error);
 247
 248 void dm_cell_visit_release(struct dm_bio_prison *prison,
 249                            void (*visit_fn)(void *, struct dm_bio_prison_cell *),
 250                            void *context,
 251                            struct dm_bio_prison_cell *cell)
 252 {
 253         unsigned long flags;
 254
 255         spin_lock_irqsave(&prison->lock, flags);
 256         visit_fn(context, cell);
 257         rb_erase(&cell->node, &prison->cells);
 258         spin_unlock_irqrestore(&prison->lock, flags);
 259 }
 260 EXPORT_SYMBOL_GPL(dm_cell_visit_release);
 261
 262 static int __promote_or_release(struct dm_bio_prison *prison,
 263                                 struct dm_bio_prison_cell *cell)
 264 {
 265         if (bio_list_empty(&cell->bios)) {
 266                 rb_erase(&cell->node, &prison->cells);
 267                 return 1;
 268         }
 269
 270         cell->holder = bio_list_pop(&cell->bios);
 271         return 0;
 272 }
 273
 274 int dm_cell_promote_or_release(struct dm_bio_prison *prison,
 275                                struct dm_bio_prison_cell *cell)
 276 {
 277         int r;
 278         unsigned long flags;
 279
 280         spin_lock_irqsave(&prison->lock, flags);
 281         r = __promote_or_release(prison, cell);
 282         spin_unlock_irqrestore(&prison->lock, flags);
 283
 284         return r;
 285 }
 286 EXPORT_SYMBOL_GPL(dm_cell_promote_or_release);
 287
 288 /*----------------------------------------------------------------*/
 289
 290 #define DEFERRED_SET_SIZE 64
 291
 292 struct dm_deferred_entry {
 293         struct dm_deferred_set *ds;
 294         unsigned count;
 295         struct list_head work_items;
 296 };
 297
 298 struct dm_deferred_set {
 299         spinlock_t lock;
 300         unsigned current_entry;
 301         unsigned sweeper;
 302         struct dm_deferred_entry entries[DEFERRED_SET_SIZE];
 303 };
 304
 305 struct dm_deferred_set *dm_deferred_set_create(void)
 306 {
 307         int i;
 308         struct dm_deferred_set *ds;
 309
 310         ds = kmalloc(sizeof(*ds), GFP_KERNEL);
 311         if (!ds)
 312                 return NULL;
 313
 314         spin_lock_init(&ds->lock);
 315         ds->current_entry = 0;
 316         ds->sweeper = 0;
 317         for (i = 0; i < DEFERRED_SET_SIZE; i++) {
 318                 ds->entries[i].ds = ds;
 319                 ds->entries[i].count = 0;
 320                 INIT_LIST_HEAD(&ds->entries[i].work_items);
 321         }
 322
 323         return ds;
 324 }
 325 EXPORT_SYMBOL_GPL(dm_deferred_set_create);
 326
 327 void dm_deferred_set_destroy(struct dm_deferred_set *ds)
 328 {
 329         kfree(ds);
 330 }
 331 EXPORT_SYMBOL_GPL(dm_deferred_set_destroy);
 332
 333 struct dm_deferred_entry *dm_deferred_entry_inc(struct dm_deferred_set *ds)
 334 {
 335         unsigned long flags;
 336         struct dm_deferred_entry *entry;
 337
 338         spin_lock_irqsave(&ds->lock, flags);
 339         entry = ds->entries + ds->current_entry;
 340         entry->count++;
 341         spin_unlock_irqrestore(&ds->lock, flags);
 342
 343         return entry;
 344 }
 345 EXPORT_SYMBOL_GPL(dm_deferred_entry_inc);
 346
 347 static unsigned ds_next(unsigned index)
 348 {
 349         return (index + 1) % DEFERRED_SET_SIZE;
 350 }
 351
 352 static void __sweep(struct dm_deferred_set *ds, struct list_head *head)
 353 {
 354         while ((ds->sweeper != ds->current_entry) &&
 355                !ds->entries[ds->sweeper].count) {
 356                 list_splice_init(&ds->entries[ds->sweeper].work_items, head);
 357                 ds->sweeper = ds_next(ds->sweeper);
 358         }
 359
 360         if ((ds->sweeper == ds->current_entry) && !ds->entries[ds->sweeper].count)
 361                 list_splice_init(&ds->entries[ds->sweeper].work_items, head);
 362 }
 363
 364 void dm_deferred_entry_dec(struct dm_deferred_entry *entry, struct list_head *head)
 365 {
 366         unsigned long flags;
 367
 368         spin_lock_irqsave(&entry->ds->lock, flags);
 369         BUG_ON(!entry->count);
 370         --entry->count;
 371         __sweep(entry->ds, head);
 372         spin_unlock_irqrestore(&entry->ds->lock, flags);
 373 }
 374 EXPORT_SYMBOL_GPL(dm_deferred_entry_dec);
 375
 376 /*
 377  * Returns 1 if deferred or 0 if no pending items to delay job.
 378  */
 379 int dm_deferred_set_add_work(struct dm_deferred_set *ds, struct list_head *work)
 380 {
 381         int r = 1;
 382         unsigned long flags;
 383         unsigned next_entry;
 384
 385         spin_lock_irqsave(&ds->lock, flags);
 386         if ((ds->sweeper == ds->current_entry) &&
 387             !ds->entries[ds->current_entry].count)
 388                 r = 0;
 389         else {
 390                 list_add(work, &ds->entries[ds->current_entry].work_items);
 391                 next_entry = ds_next(ds->current_entry);
 392                 if (!ds->entries[next_entry].count)
 393                         ds->current_entry = next_entry;
 394         }
 395         spin_unlock_irqrestore(&ds->lock, flags);
 396
 397         return r;
 398 }
 399 EXPORT_SYMBOL_GPL(dm_deferred_set_add_work);
 400
 401 /*----------------------------------------------------------------*/
 402
 403 static int __init dm_bio_prison_init_v1(void)
 404 {
 405         _cell_cache = KMEM_CACHE(dm_bio_prison_cell, 0);
 406         if (!_cell_cache)
 407                 return -ENOMEM;
 408
 409         return 0;
 410 }
 411
 412 static void dm_bio_prison_exit_v1(void)
 413 {
 414         kmem_cache_destroy(_cell_cache);
 415         _cell_cache = NULL;
 416 }
 417
 418 static int (*_inits[])(void) __initdata = {
 419         dm_bio_prison_init_v1,
 420         dm_bio_prison_init_v2,
 421 };
 422
 423 static void (*_exits[])(void) = {
 424         dm_bio_prison_exit_v1,
 425         dm_bio_prison_exit_v2,
 426 };
 427
 428 static int __init dm_bio_prison_init(void)
 429 {
 430         const int count = ARRAY_SIZE(_inits);
 431
 432         int r, i;
 433
 434         for (i = 0; i < count; i++) {
 435                 r = _inits[i]();
 436                 if (r)
 437                         goto bad;
 438         }
 439
 440         return 0;
 441
 442       bad:
 443         while (i--)
 444                 _exits[i]();
 445
 446         return r;
 447 }
 448
 449 static void __exit dm_bio_prison_exit(void)
 450 {
 451         int i = ARRAY_SIZE(_exits);
 452
 453         while (i--)
 454                 _exits[i]();
 455 }
 456
 457 /*
 458  * module hooks
 459  */
 460 module_init(dm_bio_prison_init);
 461 module_exit(dm_bio_prison_exit);
 462
 463 MODULE_DESCRIPTION(DM_NAME " bio prison");
 464 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
 465 MODULE_LICENSE("GPL");